/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jasper.el;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import javax.el.ELContext;
import javax.el.ELResolver;
import javax.el.FunctionMapper;
import javax.el.ValueExpression;
import javax.el.VariableMapper;

import org.apache.jasper.Constants;

/**
 * Implementation of ELContext
 * 
 * @author Jacob Hookom
 */
public final class ELContextImpl extends ELContext {

	private final static FunctionMapper NullFunctionMapper = new FunctionMapper() {
		public Method resolveFunction(String prefix, String localName) {
			return null;
		}
	};

	private final static class VariableMapperImpl extends VariableMapper {

		private Map<String, ValueExpression> vars;

		public ValueExpression resolveVariable(String variable) {
			if (vars == null) {
				return null;
			}
			return vars.get(variable);
		}

		public ValueExpression setVariable(String variable,
				ValueExpression expression) {
			if (vars == null)
				vars = new HashMap<String, ValueExpression>();
			return vars.put(variable, expression);
		}

	}

	private final ELResolver resolver;

	private FunctionMapper functionMapper;

	private VariableMapper variableMapper;

	public ELContextImpl() {
		this(ELResolverImpl.getDefaultResolver());
		if (Constants.IS_SECURITY_ENABLED) {
			functionMapper = new FunctionMapper() {
				public Method resolveFunction(String prefix, String localName) {
					return null;
				}
			};
		} else {
			functionMapper = NullFunctionMapper;
		}
	}

	public ELContextImpl(ELResolver resolver) {
		this.resolver = resolver;
	}

	public ELResolver getELResolver() {
		return this.resolver;
	}

	public FunctionMapper getFunctionMapper() {
		return this.functionMapper;
	}

	public VariableMapper getVariableMapper() {
		if (this.variableMapper == null) {
			this.variableMapper = new VariableMapperImpl();
		}
		return this.variableMapper;
	}

	public void setFunctionMapper(FunctionMapper functionMapper) {
		this.functionMapper = functionMapper;
	}

	public void setVariableMapper(VariableMapper variableMapper) {
		this.variableMapper = variableMapper;
	}

}
